i would like to make the data from my parrelel port into a serial stream then back again, is it encoders and decoders which i need to do this and would any1 be able to suggest suitable ics? Cheers Col
The problem here is that there is no standard way of communicating on the parallel port. It's not like data is clocked off in any standard way or anything. Maybe if you just wanted to support certain kinds of printer you might be okay, but basically you are going problems. My advice would be to look at either some kind of parallel-in serial-out shift register, or perhaps a microcontroller like a PIC or better still Atmel. You need to sample the data and control lines very fast, and continually transmit their status via the serial line. When I say fast, I mean really fast, like at least one mega-sample per second. Assuming thats 13 bits per sample, you are looking at a 15Mb serial line after including some basic control codes, and that's one way only. You can get serial line trancievers, but basically what you need to do is use voltage differentials to determine the signal rather than simple levels, if you want to be resistant to noise over any distance. It's a tricky one, but possible. Just one more though, another idea would be to make a custom ISA or PCI card with a parallel port on it. You can also get USB parallel ports but they typically tend to be only for parallel printers. MoJo
wanna make a wireless lcd, i guessed i wantedit in serial so there is only one dataline to transmit. Col
Not my area of expertese, but couldn't couldn't you use a 8 bit encoded/decoder for your project? I think that UARTs are what you want to be looking at
Yes, serial ones are only one data line. The best way I see doing this with a Parallel LCD would be to get a serial backpack for it, thus turning it into a Serial LCD.
would it be cheeper to fo that or buy a serial lcd? also with a serial does it just use 3 wires +5v ground an data? Col
It is pretty cheap to do it that way. I love my Matrix Orbital display though. You only need those 3 lines for one way serial communication (ie LCD's), 4 for 2 way.
Three wires will give you bi-directectional RS232 serial, which is enough for most LCDs. Some draw power from the serial port too, but if you are going wireless I assume you are using batteries or something so that's not an issue. You can get wireless RS232 traceivers. Another option would be to use a microcontroller (Atmel, PIC) at either end to convert RS232 to clocked serial, transmit it, and then convert back to RS232. Just take a look around for what RF chips are available and what they can do. Actually, I seem to remember that you used to be able to buy a wireless RS232 link for computers. You can certainly get IR ones, I don't know about RF. MoJo
Would this help? http://www.allelectronics.com/cgi-bin/category.cgi?category=search&item=EDE-702&type=store You should not have to receive data from the LCD, only send it. I have used that chip before. (I fried it later though)
zap i have found a similar chip in the uk, i was wondering what software you used to control your lcd when you were using it? also do they behave ok at 2400 baud as that would make transmitters and recievers a lot cheeper? Cheers Col (ps do u need 2 one at the pc end and one at the lcd end?)
Shift registers convert serial data to parallel data... (i think it's that way around, but you can probably do it both ways ) read about D-type flipflops http://www.play-hookey.com/digital/shift-in_register.html http://www.play-hookey.com/digital/shift-out_register.html
